Patent application title: SOLAR WATER HEATER RETROFITTED FROM CONVENTIONAL WATER HEATER, SYSTEM AND METHOD
Ke Ting Zheng (Henderson, NV, US)
IPC8 Class: AF24J240FI
Class name: Of fluent medium temperature responsive freezing prevention
Publication date: 2011-06-16
Patent application number: 20110139144
A solar water heater system composed of retrofitting an existing
conventional gas or electric water heater by adding a solar thermal
circulating loop, wherein a heat pipe vacuum tube solar collector, a
thermal circulating pump, a computer control system with temperature
sensors and relative three-way connections, valves and pipes are
installed on the existing water storage tank, is disclosed herein along
with the method for building the system.
1. A solar water heater system, retrofitting from add a solar thermal
circulating loop to an existing conventional gas or electric heated water
heater storage tank, wherein the loop is formed by a solar thermal
circulating pump, a heat pipe vacuum tube solar collector, a
temperature/pressure releasing valve, a vacuum brake valve, a one-way
direction valve and a computer controller; install an extension pipe
between the tank bottom drain hole and the original train valve; install
two three-way connections in a particular manner to enable the solar
thermal circulating loop being able to add: install the first three-way
connection in the added extension pipe, install the second three-way
connection in the original cold water supply pipe, the two three-way
connections' outlets form the solar thermal circulating loop's inlet and
outlet; install two one-way direction (check) valves: install the first
one-direction valve at the end of the solar thermal circulating loop to
prevent the cold supply water from entering the thermal cycle loop,
install the second one-way direction valve in the original cold water
supply pipe in front of the second add-on three-way connection to prevent
the solar thermal circulating hot water from entering the cold water
supply line; install three temperature sensors: install T1 at the solar
collector outlet, install T2 at the storage tank bottom drain hole
extension pipe, install T3 at the storage tank hot water outlet pipe;
install a computer controller to provide the solar thermal circulating
control to the system, configure the three sensors T1, T2 and T3 as the
computer controller's inputs, program the computer controller to provide
at least three outputing control signals: two outputing signal control
the two circulating pumps working in the system, one outputing signal
control a turn-on or turn-off switch which could be used for various
purpose, for example, to control the original gas or electric heater;
install a temperature missing valve on the original hot water supply pipe
to prevent the hot water supplying to the end user from getting too hot
scalding people; install the second circulating pump in the hot water
supply pipe for being able to circulate the hot water when the storage
tank water temperature reaches the highest set temperature; preferred,
install two ball valves at the solar thermal circulating loop inlet and
outlet to perform the function of shutting off the circulating loop to
the original gas or electric water heater when necessary; preferred,
install a thermal energy meter at the solar collector outlet to provide
the solar thermal energy generated in a particular time period.
2. The solar water heater system of claim 1, wherein the installed heat pipe vacuum tube solar collector header is composed of a well insulated copper or stainless steel pipe on which number of dry thermalwells are vertically soldered at the equal distance; the condensers of the heat pipes are tightly placed in these dry thermalwells; the heat pipe is centrally placed in the all glass coaxial double-layer vacuum tube, the space between the two layers of glass tube is vacuumed, there is no water flowing into the vacuum tube or the collector solar energy absorbing elements.
3. The solar water heater system of claim 1, wherein the computer control system is programmed to provide the functions to control the solar system: it controls the solar thermal energy circulating to the storage tank when the sun provide energy to heat the water; the computer controller is programmed to provide control functions for the solar water heater system to automatically work uninterrupted for four seasons, these program functions include preventing solar collector from frozen, preventing solar collector from over-heating, preventing storage tank water from over-heating, storage water anti-bacteria, etc. common issues of a solar water heater system; the controller works with the inputs from the solar collector output temperature, the existing storage water tank's lowest and highest temperature, and outputs signal controlling the solar thermal circulating pump, the hot water circulating pump and the existing gas or electric heater turn on or off as a back-up heating unit.
4. The solar water heater system of claim 1, wherein the existing water heater's gas or electric heater could be turned on or off by its original temperature-controlled system, which will turn on or off the conventional energy heater when the water temperature reaches certain set temperature, while in this retrofitting solar system, the existing conventional energy heater is only playing the back-up heater role.
CROSS REFERENCE TO RELATED APPLICATIONS
 This applications claims priority under 35 U.S.C. §119 based on Chinese Patent Application No. 201010154644.8, filed Apr. 26, 2010; Chinese Patent Application No. 201020169035.5, filed Apr. 26, 2010 and are incorporated herein by reference.
BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to solar energy application, structures and retrofitting methods and systems. In particular, this invention relates to Use an existing conventional gas or electric water heater, through a specially designed system and method, adding a solar thermal cycle loop comprised of solar collector(s), solar thermal circulating pump, the corresponding pipes and valves, and a computer automatic control system with temperature sensors, which changes the conventional gas or electric water heater into a solar water heater system.
 2. Background of the Related Art
 The domestic water heater that is currently used by most family and business providing hot water is heated by traditional energy: gas or electricity.
 A gas flame stove is installed at the bottom of the storage tank or an electric heater is installed inside the storage tank to provide heating energy to the existing domestic water heater. There are two outlets on the top of the water storage tank: one used for cold supply water pipe connection, the other for hot water pipe connection.
 There are also two valves installed on the storage tank: one drain valve at the bottom of the storage tank, one temperature/pressure valve on the top or on the side of the storage tank. An exhaust fume channel has to be installed with a gas heating water heater for CO2 emission.
 There is no present technology and retrofitting method which involves using the existing gas or electric domestic water heater, simply adding on a solar energy circulating loop to the existing storage tank with comprised control, so the domestic hot water could be heated by renewable clean solar energy and reducing carbon emission. Furthermore, these gas or electric domestic water heater are widely used by almost all buildings, the inherent inefficiency of consuming enormous amounts of traditional energy and discharging large quantity of carbon emission while wasting the solar energy shining on the building's roof is particularly apparent in the domestic water heating application.
SUMMARY OF THE INVENTION
 The invention is directed to a system and a method which, among other things, solves the aforementioned need in the art.
 It is an object to overcome the above-noted disadvantages that domestic water heater is not taking any benefit from readily available solar energy. The invention provides a system that is accomplished through the method that install a solar energy cycle loop on to the existing conventional gas or electric water heater storage tank, which include solar collectors, solar thermal circulating pump, the corresponding pipes and valves, as well as a computer automatic control system controlling the circulating pump with temperature sensors as inputs.
 In the embodiment, the invention use of traditional gas-fired or electric heated water heater thermal storage tank water drain hole to create the solar energy cycle loop inlet, which add an extension pipe between the storage tank bottom water drain hole and the original drain valve, and install a three-way connection on the pipe. The three-way connection connecting to the solar energy circulating pump forms the solar thermal cycle loop inlet, while the extended water drain valve remains its discharge function.
 Install the second three-way connection to the existing cold water supply pipe and add on two one-way direction valves (check valves): one at the output of the solar cycle loop, the other at the cold water supply pipe. The outlet of the second three-way connection forms, or connects to the solar thermal cycle loop outlet adding to the existing storage tank. The inlet of the solar thermal cycle loop, through the solar energy circulating pump, to the solar collector's one end, and then to the other end of the solar collector, through a temperature/pressure valve and a vacuum breaker valve, and then to the first one-way direction valve, connect to the outlet of the second three-way connection, or the outlet of the solar thermal cycle loop. The added first one-way direction valve installed in outlet of the solar thermal cycle loop prevents the cold supply water from entering the cycle loop; and the second one-way direction valve installed in the cold water supply pipe prevents the solar thermal circulating hot water from entering into cold supply water.
 Three temperature sensors are installed in the system to provide temperature inputs for the computer controller, sensor T1 is installed at the outlet of the solar collector, sensor T2 is installed at the first three-way connection at the bottom of the storage tank, sensor T3 is installed at the hot water outlet pipe of the storage tank.
 The computer controller provides at least three outputs: output signal to control solar thermal circulating pump, output signal to control the back-up heating unit (gas heater or electric heater), output signal to control second circulating pump connected in the hot water supply line.
 The temperature sensors T1 and T2 test both temperature from the collector header outlet and the bottom of the water storage tank, the solar thermal circulating pump is triggered by the computer controller when the preset temperature difference between the two is reached, for example T=T1-T2=8. The circulating pump regulates the flow of water from the solar collector to the tank transferring solar thermal energy into water in the storage tank. The solar thermal circulating pump is turned off by the computer controller when the temperature T1 and T2 difference reaches the preset low figure, for example T=T1-T2=4.
 The temperature sensor T3 is applied for the computer controller to provide the water storage tank high temperature protection function. The temperature sensor T3 test the high temperature for the water at the tank hot water outlet pipe, if the temperature reaches the highest allowed water temperature set up by users, computer controller will send out control signal to prevent the solar circulating pump from working even the temperature difference T=T1-T2 reaches the set pump kick-off figure; the computer controller is able to send out further signal to control second pump circulating outlet hot water to prevent the tank water temperature from exceeding the highest temperature protection point.
 It is preferred those two additional valves: one temperature/pressure valve and one vacuum breaker valve are added into the solar cycle loop at the position of the solar collector outlet point. It is also preferred to install a temperature mixing valve in the hot water outlet, which will regulate the hot water temperature in the hot water supply line.
 Furthermore, a thermal energy meter could be installed at the output of the solar collector to measure the thermal energy generated by the system, and also two shut-off ball valves could be installed at both sides of the solar thermal cycle loop to provide isolation function when needed.
 The solar collector use the all glass double-layer vacuum tube as the solar energy collecting components with the heat pipe as the thermal transferring element, and the header inside is the sealed copper or stainless steel manifold structure shown as FIG. 2, which composed of a heater pipe with number of soldered dry thermalwells. The collector header manifold collects solar thermal energy through flowing water cross these dry thermalwells and remains the water inside the collector header manifold without entering the heat pipe and vacuum tube.
 The condenser of the heat pipe inside the vacuum tube tightly placed in those dry thermalwells, transfer the solar energy collected from the vacuum tube to the water flow through the header manifold. The vacuum between the coaxial glass tubes provides the best insulation, which retains the thermal energy inside the inner tube no matter how cold the collector environment is. The solar collector header manifold is also well insulated, this prevent the water inside from being easily frozen.
 Additional control function preventing solar collector from frozen is provided by the computer controller software: when the solar collector works in an extremely cold environment, if the temperature sensor T1 test the collector header inside manifold temperature reaching to the preset low point, for example T1=35° F., the computer controller sends a signal to solar thermal circulating pump pumping the tank water flow through the header manifold; when the manifold temperature T1 reaches certain high point, for example T1=38° F., the pump stops running, which ensures the system works well in any kind of cold weather environment.
 Accordingly, the present invention provides a complete computer control software system, which provides not only the above noted basic function, but the additional control functions, such as: the maximum solar energy usage, which ensures the system use the solar energy most in any situation while only turn on the back-up heating unit as necessary; storage water temperature control, which provides the function to enable users to set up the water temperature in different levels in different seasons to store the most solar energy.
 These and other aspects of the system and method of the invention will become more readily apparent to those having ordinary skill in the art for the following detailed description of the invention taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE FIGURES
 So that those having ordinary skill in the art to which the invention pertains will more readily understand how to make and use the method and the system of the invention, embodiments thereof will be described in detail herein below with reference to the drawings, wherein:
 FIG. 1 illustrates the embodiment of the core functional components of the embodiment of the system according to the invention system and method which used the existing water heater storage tank changing the traditional gas or electric water heater into solar water heater.
 FIG. 2 shows a cross-section view of the solar collector inside manifold type header constructed for use as part of the solar thermal cycle loop added to an existing gas or electric water heater according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
 The advantages of the system and method of this invention will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred and exemplary embodiments taken in conjunction with the drawings, which are not intended to limit the scope of the invention.
 FIG. 1 schematically depicts a solar water heater system retrofitted from a conventional gas water heater in accordance with the embodiments of the invention for use in any building (including Removable Vechicle) and generally referred to as retrofitted solar water heater system which builds a new solar thermal circulating loop on to the existing gas heater storage tank 1, or the used storage tank, if still in good working condition, does not need to be replaced in this retrofitting process of changing into solar system.
 The storage tank 1 has a built-in gas heater 2 at the bottom that heats the water with a temperature controller, which forms the conventional gas water heater/boiler that is generally built with four holes: hot water outlet 3, cold water inlet 4, water drain 5, and temperature/pressure release 6, which are relatively connected with hot water supply pipe 9, cold water supply pipe 8, temperature/pressure releasing valve 10, drain valve 7. As a conventional gas water heater, an exhaust fume channel 11 is installed.
 The invention is to use the existing water heater, adding two three-way connections 12 and 13, which forms the added solar cycle loop inlet and outlet; adding an extension pipe 14 between the storage water tank drain 5 and the drain valve 7, which creates the base for installing the first three-way connection 12; and the second three-way connection 13 is installed in the cold water supply line 8.
 Between the two three-way connections 12 and 13, add on a complete solar thermal cycle loop formed with one water circulating pump 17, one solar collector 18, or several solar collectors in some embodiments, one temperature/pressure releasing valve 19, one vacuum breaker valve 20, and one one-way direction (check) valve 21, in a preferred embodiment, the solar thermal cycle loop is added to the existing gas water heater with two ball valves 15 and 16 at the two ends before connecting to the two three-way connections 12 and 13, although they are not affect the cycle loop's normal function.
 In the embodiment of FIG. 1, there are four temperature sensors T1-T4 are installed for getting temperature inputs needed for the computer controller 22, T1 is installed at the outlet 23 of the solar collector header, T2 is installed at the storage tank bottom extended pipe 14, T3 is installed at the tank hot water outlet pipe 9, T4 is installed at the hot water far away supply pipe 24.
 The computer controller 22 is installed with its electric connections with temperature sensors T1 to T4, and circulating pumps 17 and 25; in the embodiment of FIG. 1, the original gas heater temperature controller is used to turn on or off the gas heater as the back-up heating unit for the solar system based on the water temperature inside the tank and the computer controller output is not connected to the gas heater.
 The second one-direction (check) valve 26 is installed in the cold water supply pipe 8, the second circulating pump 27 is installed in the hot water supply pipe 9, and one mixing valve 27 is also installed in the hot water supply pipe 9 to regulate the output hot water temperature.
 In operation, the sunlight will heat the collector and its temperature at T1 rise, the computer controller reads the temperature difference between T1 and T2, when there is enough sun shining on the collector, the temperature difference T=T1-T2 reaches to the preset figure, the circulating pump 17 is turned on by the controller until the temperature T1 reduce result in the temperature difference T reaches another preset low figure.
 In the summer season the solar energy reaches the maximum, the water temperature in the tank could be heated to its highest point, the solar system of this invention resolves the over-heating issue with its computer controller protection function: when the controller reads the temperature T3 to a preset highest temperature allowed, for example T3=190° F., the controller turn on the circulating pump 25, which circulating the hot water from the tank through the hot water pipe line dissipating the heat on its circling. The other method to prevent the tank water from over-heating is to replace the original drain valve 7 by a solenoid valve, when the tank water temperature reach the highest temperature allowed, the controller turn on the solenoid valve, which opens directly draining the hot water out the system.
 The temperature sensor T4 provides the hot water supply line temperature figure to the controller; when the T4 is lower than a preset temperature figure, the controller turn on circulating pump 25 enabling the hot water in the pipe remain the required temperature.
 FIG. 2 illustrates the infrastructure of the solar collector heater (28 in FIG. 1) inside, which is formed with a copper or stainless steel pipe 201 shrank at both ends; there are numbers of dry thermalwells 202 made of the same material vertically soldered on the header pipe 201. The circulating water flow through the header pipe space 203 while not flow into the dry thermalwell inside taking the thermal energy from the dry thermalwell transformed from the heat pipe condenser placed inside the dry thermalwell 202 into the circulating water, and the water carries the thermal energy into the storage tank completing the solar energy transition.
 As the FIG. 2 shows that the solar collector heater structure is basically a copper or stainless steel pipe with those dry thermalwells in the middle, the whole solar thermal cycle loop added to the gas water heater basically is formed with a copper or a stainless steel pipe, which should be well insulated from the both ends when it is installed.
 Because the solar collector is using the all glass double-layer vacuum tube (18 in FIG. 1) as the solar energy absorbing elements, which provides the best insulation for the collector because of the vacuum space between the two glass walls of the tube, the nature of the heat pipe vacuum tube solar collector gives the advantage that it could be working in any time and any where, no matter how hot or cold the environment is.
 In the real application embodiment of the invention, part of the solar thermal cycle pipe could be placed outside the building and it could encounter severe cold weather, since this retrofitting solar system is running the tank inside potable water through the thermal circulating loop into the collector heater and returning, the solar system must have the ability to prevent the collector heater and the circulating pipes from frozen, the programmed computer controller's software perform the protection function, which reads the T1 temperature comparing the user preset frozen protection temperature, for example 35° F., if the T1 has reached the protection temperature, the controller signals the circulating pump 17 runs moving the water from the tank to the collector, through the circulating loop pipes and returning; when the T1 temperature increase to the certain high degree, the circulating pump stops.
 Thus, with benefit of solar energy, the system of this embodiment of the invention will reduce or eliminate the gas or electricity consumption on heating the water.
 In the exemplary descriptions provided herein there are numerous specific details set forth in order to provide a more thorough understanding of some of the embodiments of the invention. It will be apparent, however, to an artisan of ordinary skill that the present invention may be practiced without incorporating all aspects of the specific details described herein. Although the description herein is provided in sufficient detail for one skilled in the art to make, use and practice the invention, it should be understood that some specific features may have not been described in detail because, among other things, the invention should not be limited as such, and so as not to obscure the invention.
 It will be understood that certain combinations and subcombinations of the invention are of utility and may be employed without reference to other features in subcombinations. This is contemplated by and is within the scope of the present invention. As many possible embodiments may be made of this invention without departing from the spirit and scope thereof, it is to be understood that all matters hereinabove set forth or shown in the accompanying figures are to be interpreted as illustrative and not in a limiting sense.
 Those skilled in the art will recognize that the concepts, structures, systems, and methods of this disclosure may be implemented in many manners and as such this disclosure is not to be limited by the exemplary embodiments and examples set forth herein. While the particular embodiments as shown and disclosed herein are fully capable of providing the features and advantages described herein, it is to be understood that it is merely illustrative of some embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.
Patent applications by Ke Ting Zheng, Henderson, NV US